These compounds popped up after Seattle eased building restrictions on A.D.U.s in 2019, as part of the city’s efforts to increase housing density and drive down prices.

In Seattle, a single person making $44,000 a year pays up to $1,100 per month for a studio, while a family of three living on $84,840 a year spends a maximum of $2,121 a month for a two-bedroom.